An Expedition Approach

Surveying caves on expeditions can be different to surveying on your home territory due to time constraints or the fact that you may never go there again.

This is not an attempt to teach surveying but a look at a different approach for expeditions.

 

Introduction

Surveying should not be just about producing a map of the cave. It should be more about documentation - recording what the expedition found, not just in line with expedition objectives, but also about recording information which may be useful to researchers and to enable future expeditions to reduce duplicated effort.

The main task is to  produce a good map of each cave with as much relevant information as possible. It should also include writing a description of the cave with photographs if possible.

 In order to ensure that things go smoothly in the field, surveying techniques and methodology should be set out in advance of an expedition. Ideally training sessions should be organised for all team members who will be responsible for surveying, normally that would be everyone.

If it isn't possible to do this in advance, for instance if members are from different countries, then a surveying briefing should be carried out at the start of the expedition in the field. Even in this situation much can be achieved beforehand using the internet.

It is a good idea to have one person responsible for collection and collation of data with an assistant for backup.

The following should be considered during the planning process.

  • What software will be used
  • Who will draw the final maps
  • What maps will be needed
  • What specific data should be recorded
  • What additional data could be recorded if time allows

As a minimum the following data should be recorded when surveying

  • Date of survey - needed for magnetic declination
  • Survey team members
  • Name of cave being surveyed
  • Name of cave section e.g. Upper Series, Lower Levels, Show Cave Section - these will be useful when writing the description
  • Calibration data
  • Instruments used
  • Units used if not 'normal' e.g. grad, feet, percent
  • survey legs and LRUD readings

Other things that should/could be recorded

  • Major features such as stal bosses, huge blocks
  • side passages, even if you don't explore them, put a station here for use later
  • pits and steps in the floor
  • floor detail, blocks, sand, pebbles, guano, flowstone
  • avens and chimneys
  • streams with direction of flow
  • air draughts with direction
  • pitches
  • changes in passage size, good idea to place a station here
  • notches
  • passage termination - show type - boulder choke, stal choke, too low, too tight
  • waterfalls and cascades
  • inlets and sinks
  • geological features, faults slickensides, dip/strike, dikes, sills, folding
  • biological - blind fish, crabs etc, animal prints, bones
  • archaeological features, fire pits, sherds, bones

All instruments should be calibrated daily both before and after the caving trip. This will not only allow correction of instrument inaccuracies but will pick up any damage caused to instruments before further surveying trips are wasted.

A simple calibration method is to set up two stations at the camp, away from electrical interference if using DistoX, and taking forward and back readings of both azimuth and inclination. The distance between the stations will be fixed so any tape or disto errors will be spotted.

It is not normally required to do a full DistoX calibration unless batteries are being changed or you have moved to a new area, but the simple calibration will alert you to any major error.


The survey method chosen will depend on team expertise, instruments available, environment restraints. If time allows both forward and back bearings should be taken.This is essential when surveying in areas with large magnetic interference such as mines and lava tubes. For guidance on how to treat such data see http://home.utah.edu/~nahaj/cave/survey/internal-angles-example.html.

Most commonly used methods are disto, compass and clino or, more recently, paperless surveying using DistoX and PDA.


Data organisation will depend on circumstances. Most expeditions now take laptops, printers and maybe scanners.

The most important thing is data integrity. A computer crash can result in many hours of data entry having to be repeated. Backups are essential. Multiple laptops are a good idea.

The raw data should always be preserved, mistakes and all. Many people use loose leaf survey books so that yesterday's data is not at risk by taking it back into a wet cave today. Where bound survey books are used it's a good idea to scan or photograph the pages after each trip and store them on as many pen drives and laptops as possible. This also applies to loose leaf.

Even when one person has sole responsibility for survey data it's always a good idea for every team member to take a copy of the raw data home with them so that, in the case of data disasters, the original data is available somewhere.

A good method of data organisation can be seen at http://www.mulucaves.org/wordpress/surveying/the-mulu-survey-dataset

I use Therion and my data is organised along the lines of the Mulu Dataset but my directory structure is as follows

system.therion - folder/directory for the cave system

cave.therion - folder/directory for the cave

cave.th - index file for all scraps and maps

survey.therion - folder/directory for survey

survey.th - therion data file for survey

survey.th2 - scraps and maps for survey

resources - folder/directory for documents pertaining to survey

sketches

survey notes

scans

other relevant docs

output - folder/directory for output documents of the survey

survey.pdf

surveyList.html - list of entrances, caves, leads etc.

survey.3d - survex 3d model

survey.kml - Google Earth

survey.lox

survey - ESRI database folder

any other output files

survey2.therion

... etc.

output - folder/directory for output documents of the cave

cave2.therion

... etc

 output - folder/directory for output documents of the system

These structure are contained within folders for country and region.

Note: Names in bold are replaced with the names of cave system,cave, survey


http://expo.survex.com/handbook/survey/how.htm

http://www.sat.dundee.ac.uk/~arb/speleo/gpfseminar96/survey.html